Article
Optics
Muhammad Anisuzzaman Talukder, Paul Dean, Edmund H. Linfield, A. Giles Davies
Summary: This study introduces a THz QCL heterostructure designed to emit two resonant photons from each electronic relaxation between two same-parity states, predicting a significant enhancement of light intensity compared to conventional THz QCL structures through simulations.
Article
Chemistry, Multidisciplinary
Yumin Gong, Baogang Quan, Fangrong Hu, Longhui Zhang, Mingzhu Jiang, Shangjun Lin
Summary: This study experimentally demonstrates a graphene metasurface for THz field enhancement by adjusting the conductivity of the graphene patch. The results show enhancement of the THz field and provide a foundation for exploring THz-matter interactions and nonlinear optics.
Article
Chemistry, Multidisciplinary
Jie Deng, Jing Zhou, Xu Dai, Yonghao Bu, Zhifeng Li, Xiaoshuang Chen
Summary: The unique optoelectronic properties of graphene make it a promising material for THz detection, but the huge gap between graphene's atomic thickness and the long wavelength of THz radiation limits its efficiency. In this study, a cavity-antenna hybrid structure is proposed to enhance THz absorption in graphene through interference manipulation and impedance matching. The device exhibits significantly higher photoresponse under an impedance-matched condition compared to an impedance-mismatched condition.
Article
Engineering, Electrical & Electronic
Yucheng Liu, Weihao Liu, Qika Jia, Baogen Sun, Jun Chen
Summary: This article introduces an enhanced TLD boosted by resonant cavities, which significantly increases the quality factor of the resonant modes and enhances the output power by more than an order of magnitude. Furthermore, by changing the shape of the cavity, the operation modes and frequency of the TLD can be adjusted, allowing for efficient operation with high-order modes and increasing the output frequency without increasing machining difficulty, which is beneficial for developing high-power and high-frequency free-electron THz sources.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Materials Science, Multidisciplinary
Andrea Tomadin, Matteo Carrega, Marco Polini
Summary: This study investigates the theory of plasma-wave photodetection in bilayer graphene, demonstrating how quantum capacitance effects can modify the intensity of the photodetection signal. External electrical bias induced by top and bottom gates can be used to control the strength of quantum capacitance corrections and thus the photoresponse.
Article
Engineering, Electrical & Electronic
Pan Pan, Lin Zhang, Hengshan Cui, Jinjun Feng
Summary: This paper describes a terahertz power module based on a 0.34 THz traveling wave tube. The module employs a modified slow wave structure to achieve broad bandwidth. It provides high output power and gain in the frequency range of 0.33 THz to 0.355 THz.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Physics, Applied
Denis Fateev, Olga Polischuk, Konstantin Mashinsky, Ilya M. Moiseenko, Mikhail Yu Morozov, Viacheslav V. Popov
Summary: The study theoretically investigates the achievement of the laser regime by excitation of weak plasmon modes in structures based on active graphene, and proposes the use of weak plasmon modes with low radiative damping to decrease the threshold for the laser plasmon regime in periodic graphene structures.
PHYSICAL REVIEW APPLIED
(2021)
Article
Physics, Applied
M. Ryzhii, V Ryzhii, T. Otsuji, V Mitin, M. S. Shur
Summary: The response of lateral n(+)-i-n-n(+) graphene field-effect transistors (GFETs) to terahertz (THz) radiation is analyzed in this study. The nonlinearity caused by Coulomb drag and plasmonic oscillations in the GFET channel enables a resonantly strong response, which can be used for effective resonant detection of THz radiation.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Binxu Wang, Xiaoqing Luo, Yalin Lu, Guangyuan Li
Summary: This study proposes a doubly resonant graphene-metal hybrid metasurface which can achieve dynamic phase modulation covering a range of 361° while maintaining high reflectance, enabling dynamically tuneable beam steering and focusing.
Article
Engineering, Electrical & Electronic
Jiaxuan Li, Yang Yuan, Jialong Zeng, Ding He, Zhongjun Yu
Summary: This paper presents a broadband multistage low-noise amplifier (LNA) implemented using a 0.15-mu m GaAs pseudomorphic high-electron-mobility (pHEMT) process. Various bandwidth extension techniques like cascode, feedback, and gain-enhanced source-drain coupled line (SDCL) are employed. The SDCL, which combines the source and drain signals to enhance gain and compensate for gain roll-off, is proposed for the first time in this letter. These techniques are incorporated in a three-stage monolithic microwave integrated circuit (MMIC) LNA, achieving high gain with a wide bandwidth. Measurement results show that the LNA has an average gain of 24.7 dB and a noise figure (NF) of 1.7-2.8 dB in the frequency range of 0.5-24 GHz, while occupying a compact chip area of only 1.47 mm(2).
IEEE MICROWAVE AND WIRELESS TECHNOLOGY LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Chia-Chien Huang
Summary: A new waveguide structure is proposed, which achieves an ultraconfined mode area by coupling a dielectric waveguide and an image graphene plasmon (IGP) mode. This structure offers plasmon wavelengths 20 times shorter and normalized propagation lengths twice longer than conventional graphene plasmons (GPs). The highly integrated and enhanced nonlinear features make it suitable for building THz devices for sensing and imaging applications.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Multidisciplinary Sciences
Mohammad Alibakhshikenari, Bal S. Virdee, Shahram Salekzamankhani, Sonia Aissa, Chan H. See, Navneet Soin, Sam J. Fishlock, Ayman A. Althuwayb, Raed Abd-Alhameed, Isabelle Huynen, James A. McLaughlin, Francisco Falcone, Ernesto Limiti
Summary: This research demonstrates the effectiveness of using SIW technology to enhance the performance of antenna arrays for sub-THz integrated circuit applications, achieving significant improvements in isolation, radiation gain, and efficiency. The proposed approach shows the viability of developing antenna arrays for sub-THz integrated circuits.
SCIENTIFIC REPORTS
(2021)
Article
Physics, Applied
V. Ryzhii, T. Otsuji, M. Ryzhii, V. Mitin, M. S. Shur
Summary: This study demonstrates that resonant plasmonic detection significantly enhances the sensitivity of terahertz detectors based on a gated graphene field-effect transistor structure. By utilizing gated p and n regions as hole and electron reservoirs and terahertz resonant plasma cavities, the proposed device achieves terahertz signal rectification and excitation of plasmonic oscillations, leading to a substantial increase in detector responsivity.
PHYSICAL REVIEW APPLIED
(2022)
Article
Optics
Durgesh Kumar, Gopisetty Naga Manikanta Sai Karthik, Sanjay Kumar, Pushpa Giri, Gaurav Varshney
Summary: This article investigates the state conversion of graphene loop in the slotted antenna radiator to achieve tunable band-notch characteristics in an ultra-wideband antenna. The chemical potential of graphene can be adjusted to transform the non-resonant state to the resonant state, leading to the formation of multiple higher order resonances and the creation of band-notch characteristics. The frequency of the notched band can be tuned by varying the chemical potential. However, the conversion of the state of the graphene loop deteriorates the far-field radiation parameters and radiation efficiency of the antenna. Therefore, a trade-off needs to be made to find the desired values of gain, radiation efficiency, and frequency of the band notch. Furthermore, another technique utilizing double graphene loops with less surface area has been studied to improve the radiation efficiency of the antenna while maintaining the band-notch characteristics.
OPTICAL ENGINEERING
(2022)
Article
Physics, Multidisciplinary
Guido Homann, Jayson G. Cosme, Ludwig Mathey
Summary: This paper demonstrates the possibility of amplifying terahertz radiation in cuprate superconductors through parametric driving, and obtains relevant results through simulation experiments.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Victor Ryzhii, Maxim Ryzhii, Akira Satou, Vladimir Mitin, Michael S. Shur, Taiichi Otsuji
Summary: The injection of ballistic electrons can lead to terahertz radiation and be utilized for optimizing devices through effective Coulomb drag and plasma instability.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2022)
Article
Chemistry, Analytical
Michael Shur, Gregory Aizin, Taiichi Otsuji, Victor Ryzhii
Summary: Short-channel field-effect transistors (FETs) show potential for supporting the transition to 6G communications in the sub-THz and THz frequencies. Plasmonic crystals formed by TeraFET arrays can detect radiation intensity and phase, enabling line-of-sight terahertz (THz) detection, spectrometry, amplification, and generation for 6G communication. The ballistic and quasi-ballistic electron transport in TeraFET channels determine their response at sub-THz and THz frequencies.
Review
Nanoscience & Nanotechnology
Taiichi Otsuji, Stephane Albon Boubanga-Tombet, Akira Satou, Deepika Yadav, Hirokazu Fukidome, Takayuki Watanabe, Tetsuya Suemitsu, Alexander A. Dubinov, Vyacheslav V. Popov, Wojciech Knap, Valentin Kachorovskii, Koichi Narahara, Maxim Ryzhii, Vladimir Mitin, Michael S. Shur, Victor Ryzhii
Summary: This paper reviews recent advancements in graphene-based plasmonic metamaterials for terahertz (THz) laser transistors. The researchers investigate various approaches using graphene plasmonic metamaterials to achieve room-temperature, dry-cell-battery operated intense THz lasing with fast direct modulation. The paper discusses device structures and design constraints for coherent light sources applicable to future THz wireless communication systems.
Article
Physics, Applied
M. Ryzhii, V Ryzhii, T. Otsuji, V Mitin, M. S. Shur
Summary: The response of lateral n(+)-i-n-n(+) graphene field-effect transistors (GFETs) to terahertz (THz) radiation is analyzed in this study. The nonlinearity caused by Coulomb drag and plasmonic oscillations in the GFET channel enables a resonantly strong response, which can be used for effective resonant detection of THz radiation.
APPLIED PHYSICS LETTERS
(2022)
Article
Optics
Yuma Takida, Kouji Nawata, Takashi Notake, Taiichi Otsuji, Hiroaki Minamide
Summary: A nonlinear optical mixing technique is used to detect and characterize sub-nanosecond terahertz (THz)-wave pulses. The frequency up-conversion and parametric amplification methods are employed for sensitive detection and intensity cross-correlation characterization. The experimental results reveal the temporal profile of THz-wave pulses generated by the injection-seeded THz-wave parametric generator (is-TPG) in the tunable range of 0.95-2.00 THz to have a pulse width of 150-190 ps at full width at half-maximum.
Article
Optics
D. S. Ponomarev, D. Lavrukhin, N. Zenchenko, T. Frolov, I. A. Glinskiy, R. A. Khabibullin, G. M. Katyba, V. N. Kurlov, T. Otsuji, K. Zaytsev
Summary: We present a sapphire-fiber-based lens that enhances the emitted THz power of a large-area photo-conductive antenna (PCA). Numerical simulations demonstrate the effectiveness of the lens in redistributing the photocarriers density in the PCA's gap. We also propose a step-by-step process to precisely and controllably place the sapphire-fiber on the surface of a single PCA.
Article
Engineering, Electrical & Electronic
Eiichi Sano, Masayuki Ikebe
Summary: This article validates an analytical transmission-line method for calculating the inter-decoupling ratio of NSS and proposes a simplified method based on variational method and EM duality concept. The devised method can reproduce the measured results of commercially available NSS with high accuracy and shorter computational time compared to numerical full-wave EM simulators.
IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY
(2022)
Article
Physics, Applied
V. Ryzhii, T. Otsuji, M. Ryzhii, V. Mitin, M. S. Shur
Summary: This study demonstrates that resonant plasmonic detection significantly enhances the sensitivity of terahertz detectors based on a gated graphene field-effect transistor structure. By utilizing gated p and n regions as hole and electron reservoirs and terahertz resonant plasma cavities, the proposed device achieves terahertz signal rectification and excitation of plasmonic oscillations, leading to a substantial increase in detector responsivity.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
V. Ryzhii, M. Ryzhii, V. Mitin, M. S. Shur, T. Otsuji
Summary: The Zener-Klein interband tunneling in graphene layers can be utilized for processing and generation of terahertz signals, with negative dynamic conductance and transit-time instability. By using periodic cascade structures, THz amplification and radiation can be achieved.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Optics
Dmitry S. Ponomarev, Denis Lavrukhin, Igor A. Glinskiy, Alexander E. Yachmenev, Nikolay Zenchenko, Rustam A. Khabibullin, Yurii G. Goncharov, Taiichi Otsuji, Kirill I. Zaytsev
Summary: This study proposes the design of a photoconductive antenna (PCA) emitter with a plasmonic grating featuring a very high plasmonic Au electrode with a thickness of 170 nm. Numerical simulations show that increasing h leads to the excitation of higher-order plasmon guided modes in the Au slit waveguides, resulting in an additional increase in the emitted THz power. The fabricated PCA demonstrates efficient operation with low-power laser excitation, achieving an overall THz power of 5.3 mu W over a bandwidth of approximately 4.0 THz, corresponding to a conversion efficiency of 0.2%. This design holds promise for modern THz spectroscopic and high-speed imaging applications.
Article
Optics
Koichi Tamura, Chao Tang, Daichi Ogiura, Kento Suwa, Hirokazu Fukidome, Yuma Takida, Hiroaki Minamide, Tetsuya Suemitsu, Taiichi Otsuji, Akira Satou
Summary: In this study, a new epitaxial graphene field-effect transistor with an asymmetric dual-grating-gate (ADGG) structure was designed and fabricated to achieve fast and sensitive detection of terahertz radiation. The experimental results demonstrated its promising performance in high-speed wireless communication systems.
Article
Physics, Applied
V. Ryzhii, C. Tang, T. Otsuji, M. Ryzhii, V. Mitin, M. S. Shur
Summary: We evaluated THz detectors based on graphene channel (GC) and a floating metal gate (MG) separated from GC by a black-phosphorus (b-P) or black-arsenic (b-As) barrier layer (BL). The operation of these GC-FETs involves heating of the two-dimensional electron gas in GC by THz radiation, leading to thermionic emission of hot electrons from GC to MG. This results in variation of the floating gate potential, affecting the source-drain current. At THz radiation frequencies close to plasmonic resonance frequencies in the gated GC, the variation in source-drain current and detector responsivity can be resonantly large.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Omnia Samy, Mohamed Belmoubarik, Taiichi Otsuji, Amine El Moutaouakil
Summary: This study presents a thin THz absorber that can be easily tuned through the whole THz range (0.1-10 THz) by applying a low gate voltage (<1 V). The structure is based on cheap and abundant materials (MoS2/graphene). The absorptance frequency and width can be controlled by varying the structure and substrate dimensions, making it a promising alternative to expensive THz metamaterial-based absorbers.
Article
Nanoscience & Nanotechnology
V. Ryzhii, C. Tang, T. Otsuji, M. Ryzhii, S. G. Kalenkov, V. Mitin, M. S. Shur
Summary: In this study, we investigate the response of the micromechanical field-effect transistors (MMFETs) to terahertz (THz) signals. The MMFET utilizes microcantilevers (MC) as a floating gate and the movable mirror of Michelson optical interferometer. The mechanical vibrations of MC are converted into optical signals, allowing MMFET to operate as a THz radiation detector. The combination of mechanical and plasmonic resonances in MMFET, along with optical amplification, enables effective THz detection.
Article
Nanoscience & Nanotechnology
Juan A. Delgado-Notario, Wojciech Knap, Vito Clerico, Juan Salvador-Sanchez, Jaime Calvo-Gallego, Takashi Taniguchi, Kenji Watanabe, Taiichi Otsuji, Vyacheslav V. Popov, Denis V. Fateev, Enrique Diez, Jesus E. Velazquez-Perez, Yahya M. Meziani
Summary: This study fabricated a graphene terahertz field-effect transistor with an asymmetric-dual-grating-gate and a continuous graphite back-gate, which enhanced the THz rectified signal by forming abrupt junctions with different potential barriers. This paves the way for new record performances of graphene THz nano-photodetectors.
